the mixture screw is under a aluminum cap on the top of the carb. a small drill hole and a pick will remove the cap. you can't see it if the cap is still in place.

 

Oh, OK. I never adjusted one and reckon that's why. I remembered a small screw on the top sorta in front of that plug but didn't remember being able to turn it. Learn something everyday

Thanks Bagga

 

Here's a guy's site that I used for rebuilding my keihin carb, good stuff in that article about the history of that carb...

http://pweb.jps.net/~splaxco/hawgstuff/

Look at the keihin1 - 6.jpgs. Print them out for reference, looks like it was from a mag. in the late '70s. (Never got my accelerator pump nozzle to move), haha.

I used a dental pick to ream out the 50 low jet (had #52 incase I over reamed it) and it made a world of difference in the lean/idle problems I had, but your running rich. Maybe those missing o-rings and such may have you doing a rebuild. Good luck!

 

Thanks for that info...yes, I already rebuilt the carb about 6 months ago and had a copy of that old easy riders doc sent to me by another guy from the forums here...it helped a lot with the rebuild and I was able to turn my pump nozzle with a small wrench to aim it just right.

I found an o-ring that was extra from my rebuild kit so I just need the washer that I seem to have lost. And I found a website that has them and placed an order...you get the washer, o-ring and spring....and it is good for the a/f mixture needle on keihin butterfly and CV carbs. He also sells an ez-just needle for the CVs...here is the website in case anyone is interested:

http://www.johnsmotorcycleparts.com/

I ordered extra jets too...Just for reference for anyone who might need keihin butterfly jets, here are some part numbers:

Slow jets:
.50 27302-84
.52 27329-83
.65 27896-79
.68 27894-78
.70 27895-78
.72 27897-78
.88 27348-77
1.00 27348-76

Main Jets:
165 27419-76
170 27418-76
175 27417-76
180 27416-76

Some might be obsolete and the "inbetween" jet sizes can be gotten from custom chrome, J & P Cycles and I have some Yost jets ( .54 & .58) on order from this website:

http://www.phatperformanceparts.com/default.asp

Right now I am just waiting on the parts I ordered and still just pondering what could have changed to cause the problem.

 

Just an update....I received the carb mixture needle repacking kit and the 54 and 58 jets...installed each and still the same symptoms: The idle-mixture screw needs to be almost completely backed out before the idle smooths out...according to the easy-riders article, normal is in the 1/2 to 1 1/2 turns out range while mine is maybe 4 turns and then the needle is loose because it is beyond the tension of the spring. The slow jet size does not seem to matter...they all reacted the same way.

I checked the voes out completely and it is functioning normally.

I have been looking at a diagram of the idle circuit of the carb...I think maybe I have an obstruction between the idle port and the idle transfer ports. I have tried spraying carb cleaner and compressed air but still no success in getting this thing to run right.

It is weird because the bike ran fine when we left on a recent trip but halfway though the bike became rough to start and started stumbling and hesitating when just moving from a stop. Once it gets going the bike feels fine. So I am still thinking it has something to do with that carb idle circuit and the problem of adjusting the mixture. Any other ideas?

 

I know the intake parts were replaced and recently checked, but those are classic symptoms of an intake leak... and/or blocked idle circuit, assuming the needle isn't sticking or the float level has gotten low. A weak ignition would show up as fouling plugs and the only other idea I have at the moment would be leaking intake valves (causing low intake vacuum).

 

I have sprayed WD40 at the manifold connections to the carb and to the the engine and get no change in idle...could there still be a leak that I am not detecting ? any other good ways to check it?

I have checked electrical connections without finding any problems yet. I made continuity/resistance checks on the coil, ignition module, voes, all test ok, and replaced plugs and plug wires. What would you suggest to confirm or rule out a weak ignition? Is there a spark test that would confirm a problem there?

Or if I have leaking intake valves what should I test? Should I buy a compression tester for that? I have never looked into leaking valves before.

 

Here's what I'd do at this point and keep in mind I'm gun shy explaining procedures, especially when they involve tedious and time consuming steps, but here I go again...

First, check the float level this way:

Remove the overflow tube from the bottom rear of the bowl and replace it with a piece of clear vinyl tubing. Loosen the drain screw located on the engine side of the bowl at the bottom and drain the bowl (with fuel switch off). Next, get the bike level as possible and using a level, get the carb near perfect as you can to level, both ways, front-to-rear and side-to-side. (You'll probably have to loosen the hose clamps behind the flange adapter)

Now, make a loop with the clear tube so it is not kinked and the end comes above the mating surface of the carb body and the bowl. Tie, tape or wire it so it'll stay there for testing. With the drain screw still open, turn the fuel on and the bowl and the tube will fill. Look closely where the fuel line is in the tube - that's your fuel level. It should be within 1mm (plus or minus) of the mating surface. If it's off more than 3mm low, you need to correct that.

If that checks out OK then pull the carb and disassemble completely. Here's part of a post from a while back, (I'm tired of typing) that will hopefully explain enough of the rest;

The holes where the idle fuel comes thru are behind the butterfly on the manifold side and they are very tiny. It takes nearly nothing to plug them and it's almost impossible to get a wire into them. I'd recommend you take it off again, disassemble and soak the body in denatured alcohol. You can get it about any hardware or paint store. It's the only thing that effectively cuts varnish. Carb cleaner these days is mostly junk, thanks to EPA regs. Then use high pressure to blow thru everything. You need to remove the idle mixture screw when you do this.

And of course, when you have it off check the possibility that prodrag1320 mentioned concerning the possibility the shaft bore is worn out.

 

Not trying to be a smartass here (honest), but if you find a cv carb, a Mikuni HSR42, or even an S&S, you would be much happier with the carb, and your bike. You will wish you had done it 20 years ago...

 

I'm with Dan. If you really try hard with the OEM carb, you can achieve Suck. This sounds like a good excuse to get a CV or S&S. I personally prefer to buy new carbs, as I assume any used carb is not on the vehicle it was on for a reason (that is, it was running like crap.)